1. Field of the Invention
A subject matter of the present invention is a catalytic reactor comprising at least one architecture comprising a catalytic ceramic or metal foam of controlled macroporosity and controlled microstructure, and at least one standard architecture. Standard architecture is understood to mean the architectures conventionally employed by manufacturers of catalysts, namely drums, rods, beads, tablets, and the like.
2. Related Art
The performances of fixed bed catalytic reactors, in particular steam reforming reactors, are directly related to the structure of the catalytic bed. Structure of the catalytic bed is understood to mean the stacking of the catalysts of identical or different architecture (drums, spheres, rods, and the like) in the associated industrial reactor. Cellular structures have not currently been developed at the industrial level. Mention will be made, by way of example, of the various stacks in water-gas shift reactors (reactor involved in the water-gas reaction) (successive catalytic beds of identical architecture but of different microstructure). In these scenarios, a catalytic bed structure present in an industrial reactor can be the successive stacking of a volume A of catalyst, of a volume B of catalyst and of a volume C of catalyst. A, B and C differ either in their architecture(s) (geometric form, stack porosity, and the like), or in their microstructure(s) (chemical formulation, size of the micropores, size and distributions of active phases, and the like), or in their architecture(s)/microstructure(s). Generally, the standard architecture of catalytic beds is composed of drums comprising one or more holes, of pills, of rods, of spheres, and the like.
A high performance catalytic bed structure has to simultaneously:
exhibit a maximum surface area/volume ratio (m2/m3), in order to increase the exchange geometric surface area and thus indirectly the catalytic effectiveness,
improve the density of the filling of a tube in comparison with a random filling brought about by conventional structures (sphere, pellet, cylinder, drum, and the like),
minimize pressure drops along the bed (between the inlet and the outlet of the catalytic reactor),
provide heat transfer of increased maximum axial and/or radial effectiveness. Axial is understood to mean along the axis of the catalytic reactor and radial is understood to mean from the internal or external wall of the catalytic reactor to the center of the catalytic bed,
meet the thermomechanical and/or thermochemical stresses endured by the bed.
The overall structuring of a fixed bed catalytic reactor is a multiscale “phenomenon”:
the microstructure of the material (catalyst) itself, namely its chemical formulation, the micro- and/or mesoporosity, the size and the dispersion of the active phase(s), the thickness of the deposited layer(s), and the like,
the architecture of the catalyst, that is to say its geometric form (granules, drums, honeycomb monoliths, cellular structures of foam type, spheres, pills, rods, and the like),
the structure of the bed within the reactor (successive stacking of several volumes of catalytic materials which are different either in terms of microstructure, or in terms of architecture, or both), that is to say the arrangement of the catalytic materials of controlled architecture and/or controlled microstructure within the catalytic reactor. It is possible to envisage, for example, as structure of catalytic bed(s), successive stacks with or without the addition of noncatalytic elements of varied functionalities.
Starting from this, a problem which arises is that of providing a catalytic reactor exhibiting an improved performance.